JP5406021B2 - Crosslinked product of propylene-based resin composition, method for producing the crosslinked product, and crosslinked molded product comprising the crosslinked product - Google Patents

Description

  The present invention relates to a crosslinked product obtained by irradiating a propylene-based resin composition containing a crosslinking aid with ionizing radiation, a method for producing the crosslinked product, and a crosslinked molded product comprising the crosslinked product.

  Propylene-based polymers are materials that have better heat resistance, mechanical strength, and scratch resistance than ethylene-based polymers (ethylene-based elastomers), and the molded products are used in a wide range of applications. For example, as a molded body composed of a propylene polymer and an inorganic filler, particularly a flame retardant, an electric wire or a wire harness that requires scratch resistance is known. Moreover, the molded object obtained from a general polypropylene and an inorganic filler is also excellent in mechanical strength.

  However, the above-described molded body has the above properties, but is inferior in flexibility. With respect to this problem, Patent Document 1 discloses a flame retardant polypropylene resin composition comprising a polypropylene resin and an inorganic flame retardant. However, a molded article obtained from the resin composition has a heat resistance. There is a problem that is not enough.

  Patent Document 2 discloses a flame retardant resin composition containing a propylene-ethylene block copolymer and a polyolefin-rubber thermoplastic elastomer as a polymer component, and a metal hydroxide. However, the molded body obtained from the flame retardant resin composition has a problem that the wear resistance and heat resistance are not sufficient.

Furthermore, the propylene polymer has a problem that it is difficult to crosslink. For this reason, for applications that require high heat resistance and other properties, cross-linked molded products obtained from ethylene-based polymers that are easily cross-linked by peroxide, silane, electron beam, etc., and ethylene-based polymers and inorganic fillers are used. A crosslinked molded product obtained from an agent is used. However, the above-mentioned crosslinked molded article has a problem that it is inferior in scratch resistance, and a crosslinked molded article excellent in both heat resistance and scratch resistance has not yet been obtained.
JP 2003-313377 A Japanese Patent Laid-Open No. 2000-026696

  An object of the present invention is to provide a crosslinked product excellent in heat resistance and scratch resistance obtained by irradiating a resin composition containing a propylene-based polymer with ionizing radiation. Another object of the present invention is to provide a cross-linked molded body comprising the cross-linked body, and an electric wire insulator or a wire sheath using the cross-linked molded body.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors are able to crosslink a propylene resin composition containing a specific propylene polymer and a crosslinking aid by irradiating with ionizing radiation. The inventors have found that a cross-linked product of a propylene-based resin composition that is superior in heat resistance to conventional polypropylene can be obtained, and have completed the present invention.

  That is, the present invention relates to the following [1] to [8].

  [1] 15 to 99% by mass of a propylene polymer (A) having a melting point of 120 to 170 ° C. measured with a differential scanning calorimeter (DSC), and a melting point of 120 with a differential scanning calorimeter (DSC). A propylene-based resin containing 1 to 85% by mass of a propylene-based polymer (B) whose melting point is not observed or less than 0 ° C. (here, the total amount of the component (A) and the component (B) is 100% by mass). A crosslinked product obtained by irradiating a propylene-based resin composition containing 100 parts by mass and 0.1 to 5 parts by mass of a crosslinking aid (C) by irradiating with ionizing radiation.

  [2] The crosslinked product according to [1], wherein the propylene-based resin composition further includes 30 to 300 parts by mass of an inorganic filler (D) with respect to 100 parts by mass of the propylene-based resin.

  [3] The crosslinked product according to [2], wherein the inorganic filler (D) is at least one selected from a metal hydroxide, a metal carbonate, and a metal oxide.

  [4] The crosslinked product according to any one of [1] to [3], wherein the crosslinking assistant (C) is triallyl cyanurate or triallyl isocyanurate.

  [5] The propylene-based polymer (A) contains 50 to 100 mol% of a structural unit derived from propylene and 0 to 50 mol% of a structural unit derived from an α-olefin having 2 to 20 carbon atoms other than propylene ( Here, the total of the structural unit derived from propylene and the structural unit derived from α-olefin having 2 to 20 carbon atoms other than propylene is 100 mol%.), The propylene polymer (B) is propylene. 40 to 100 mol% of structural units derived from, and 0 to 60 mol% of structural units derived from α-olefins having 2 to 20 carbon atoms other than propylene (here, structural units derived from propylene and carbons other than propylene The sum total with the structural unit derived from an α-olefin having 2 to 20 atoms is 100 mol%.) The crosslinked product according to any one of [1] to [3].

  [6] The method includes the step of producing a molded product by molding the propylene-based resin composition according to any one of [1] to [3], and the step of crosslinking the product by irradiating with ionizing radiation. A method for producing a crosslinked product.

  [7] A cross-linked molded article comprising the cross-linked product according to any one of [1] to [3].

  [8] The crosslinked molded article according to [7], which is an electric wire insulator or electric wire sheath.

  The crosslinked product and crosslinked product of the propylene-based resin composition of the present invention have excellent scratch resistance and heat resistance. Furthermore, when the said propylene-type resin composition contains an inorganic filler, the crosslinked body and crosslinked molded object which were excellent in the flame retardance can be obtained.

  Hereinafter, the cross-linked product of the present invention, the method for producing the cross-linked product, and the cross-linked molded product composed of the cross-linked product will be specifically described.

[Crosslinked product]
The cross-linked product of the present invention is a propylene-based resin composition containing a propylene-based resin (A) and a propylene-based polymer (B) described below, and a cross-linking aid (C) at a specific ratio. Further, it is obtained by crosslinking by irradiating ionizing radiation.

<Propylene polymer (A)>
Examples of the propylene polymer (A) used in the present invention include a propylene homopolymer or a copolymer of propylene and at least one α-olefin having 2 to 20 carbon atoms other than propylene. . Here, the α-olefin having 2 to 20 carbon atoms other than propylene is an α-olefin having 2 to 20 carbon atoms other than propylene containing ethylene.

  Specific examples of the α-olefin having 2 to 20 carbon atoms other than propylene include ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and 1-decene. , 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene and the like, ethylene or α-olefin having 4 to 10 carbon atoms is preferable. These α-olefins may form a random copolymer with propylene or a block copolymer.

  Among all the structural units of the propylene polymer (A), the structural unit derived from propylene is usually 50 to 100 mol%, preferably 50 to 95 mol%, more preferably 65 to 90 mol%, and further preferably 70 to 90. It is included in the proportion of mol%. Moreover, in all the structural units of the propylene polymer (A), the structural unit derived from the α-olefin is usually 0 to 50 mol%, preferably 5 to 50 mol%, more preferably 10 to 35 mol%, Preferably it is contained in a proportion of 10 to 30 mol%. Here, the total of the structural unit derived from propylene and the structural unit derived from the α-olefin is preferably 100 mol%.

  The propylene polymer (A) used in the present invention has a melt flow rate (MFR; ASTM D1238, temperature 230 ° C., load 2.16 kg) usually from 0.01 to 1000 g / 10 minutes, preferably from 0.05 to It is in the range of 100 g / 10 min, more preferably 0.1-50 g / 10 min.

  The propylene polymer (A) used in the present invention has a melting point (Tm) measured by a differential scanning calorimeter (DSC) of 120 ° C. or higher, preferably 120 to 170 ° C., more preferably 125 to 165 ° C. Is in range.

  The propylene polymer (A) used in the present invention may have either an isotactic structure or a syndiotactic structure, but preferably has an isotactic structure in terms of heat resistance.

  Moreover, two or more types of propylene polymers (A) can be used in combination as required, and for example, two or more types of propylene polymers (A) having different melting points and rigidity can be used in combination.

  In addition, as the propylene polymer (A), homopolypropylene having excellent heat resistance (a known homopolypropylene having a copolymer component other than propylene of 3 mol% or less) and excellent balance between heat resistance and impact resistance. Block polypropylene (generally known block polypropylene having an n-decane-eluting rubber component of 3 to 30% by mass), or random polypropylene excellent in the balance between flexibility and transparency (melting measured with a differential scanning calorimeter (DSC)) A known random polypropylene having a peak of 120 ° C. or higher, preferably in the range of 125 ° C. to 150 ° C. may be selected and used in order to obtain the desired physical properties, or these may be used in combination.

  The propylene polymer (A) used in the present invention is, for example, a solid catalyst component containing magnesium, titanium, halogen and an electron donor as essential components, a Ziegler catalyst system comprising an organoaluminum compound and an electron donor, or a metallocene. It can be produced by homopolymerizing propylene or copolymerizing propylene and the α-olefin using a metallocene catalyst system containing a compound as one component of the catalyst.

<Propylene polymer (B)>
Examples of the propylene polymer (B) used in the present invention include a propylene homopolymer or a copolymer of propylene and at least one α-olefin having 2 to 20 carbon atoms other than propylene. . Here, examples of the α-olefin having 2 to 20 carbon atoms other than propylene include the same α-olefin as in the case of the propylene-based polymer (A), and preferred α-olefins are also the same. These α-olefins may form a random copolymer with propylene or a block copolymer.

  Among all the structural units of the propylene-based polymer (B), the structural unit derived from propylene is usually 40 to 100 mol%, preferably 40 to 99 mol%, more preferably 40 to 92 mol%, still more preferably 50 to 90. The constituent unit derived from an α-olefin having 2 to 20 carbon atoms other than propylene contained as a comonomer in a proportion of mol% is usually 0 to 60 mol%, preferably 1 to 60 mol%, more preferably 8 It is contained in a proportion of ˜60 mol%, more preferably 10 to 50 mol%. Here, the total of the structural unit derived from propylene and the structural unit derived from an α-olefin having 2 to 20 carbon atoms other than propylene is preferably 100 mol%.

  The propylene polymer (B) used in the present invention has a melt flow rate (MFR; ASTM D1238, temperature 230 ° C., load 2.16 kg) usually in the range of 0.1 to 50 g / 10 min.

  The propylene-based polymer (B) used in the present invention has a melting point (Tm) measured by differential scanning calorimetry (DSC) of less than 120 ° C. or no melting point is observed. It is below 100 ° C. or no melting point is observed. Here, that the melting point is not observed means that a crystal melting peak having a heat of crystal melting of 1 J / g or more is not observed in the range of −150 to 200 ° C. The measurement conditions are as described in the examples.

  The propylene-based polymer (B) used in the present invention has an intrinsic viscosity [η] of usually 0.01 to 10 dl / g, preferably 0.05 to 10 dl / g. The intrinsic viscosity [η] can be obtained from a measured value obtained by measuring the viscosity of a decalin solution at a temperature of 135 ° C. in which a polymer sample is dissolved using an Ubbelohde viscometer.

The propylene-based polymer (B) preferably has a triad tacticity (mm fraction) measured by ¹³ C-NMR of 85% or more, more preferably 85 to 97.5%, still more preferably 87 to 97%. Particularly preferably, it is in the range of 90 to 97%. When the triad tacticity (mm fraction) is in this range, the balance between flexibility and mechanical strength is particularly excellent, which is suitable for the present invention. The mm fraction can be measured by the method described in International Publication No. 2004-087775 pamphlet, page 21, line 7 to page 26, line 6.

  The production method of the propylene-based polymer (B) is not particularly limited, but a known catalyst capable of stereoregular polymerization of an olefin with an isotactic structure or a syndiotactic structure, for example, a solid titanium component and an organometallic compound is mainly used. It can be produced by homopolymerizing propylene or copolymerizing propylene and the above α-olefin in the presence of a catalyst as a component or a metallocene catalyst using a metallocene compound as one component of the catalyst. In addition, it can be produced by homopolymerizing propylene or copolymerizing propylene and the α-olefin using a known catalyst capable of polymerizing olefin with an atactic structure. Preferably, as described later, in the presence of a metallocene catalyst, it can be produced by copolymerizing propylene and an α-olefin having 2 to 20 carbon atoms other than propylene.

  Specific examples of the propylene-based polymer (B) having the above-described characteristics include a propylene / α-olefin random copolymer (B-1) having 4 to 20 carbon atoms. Hereinafter, the propylene / α-olefin random copolymer (B-1) having 4 to 20 carbon atoms that is preferably used in the present invention will be described in detail.

<< Propylene / C4-C20 α-olefin random copolymer (B-1) >>
The propylene / C4-20 α-olefin random copolymer (B-1) preferably used in the present invention is a propylene-derived constituent unit and a C4-20 α-olefin-derived constituent unit. And satisfy the following (a) and (b).
(A) The molecular weight distribution (Mw / Mn) measured by gel permeation chromatography (GPC) is 1-3.
(B) Melting point (Tm) (° C.) and the content M (mol%) of the structural unit derived from an α-olefin having 4 to 20 carbon atoms determined by ¹³ C-NMR spectrum measurement are as follows: Satisfy (1).

146 exp (−0.022 M) ≧ Tm ≧ 125 exp (−0.032 M) (1)
The melting point (Tm) of the α-olefin random copolymer (B-1) having 4 to 20 carbon atoms is measured by DSC as follows. That is, a sample was packed in an aluminum pan, heated to 200 ° C. at 100 ° C./min and held at 200 ° C. for 5 minutes, then cooled to −150 ° C. at 10 ° C./min, and then 200 ° C. at 10 ° C./min. The temperature of the endothermic peak observed when the temperature is raised to is the melting point (Tm). This melting point (Tm) is usually less than 120 ° C, preferably 100 ° C or less, more preferably in the range of 40 to 95 ° C, and further preferably in the range of 50 to 90 ° C. When the melting point (Tm) is within the above range, a crosslinked molded article having an excellent balance between flexibility and mechanical strength can be obtained. Moreover, since the stickiness of the surface of the crosslinked molded body is suppressed, the crosslinked molded body of the present invention obtained from the propylene composition has an advantage that it is easy to construct.

In the α-olefin random copolymer (B-1) having 4 to 20 carbon atoms, the crystallinity measured by (c) X-ray diffraction is preferably 40% or less, more preferably 35%. It is as follows.

  In the α-olefin random copolymer (B-1) having 4 to 20 carbon atoms in propylene, the content of the structural unit derived from propylene is preferably 50 to 95 mol%, more preferably 65 to 80 mol%, Content of the structural unit derived from a C4-C20 alpha olefin becomes like this. Preferably it is 5-50 mol%, More preferably, it is 20-35 mol%. As the α-olefin having 4 to 20 carbon atoms, 1-butene is particularly preferably used. Here, the total of the structural unit derived from propylene and the structural unit derived from the α-olefin is preferably 100 mol%.

  Such a propylene / α-olefin random copolymer having 4 to 20 carbon atoms can be obtained by, for example, a method described in International Publication No. 2004-087775.

<Crosslinking aid (C)>
Specific examples of the crosslinking aid (C) used in the present invention include sulfur, p-quinonedioxime, p, p′-dibenzoylquinonedioxime, N-methyl-N-4-dinitrosoaniline, Nitrosobenzene, diphenylguanidine, trimethylolpropane-N, N′-m-phenylene dimaleimide, divinylbenzene, triallyl cyanurate (TAC) and triallyl isocyanurate (TAIC) are preferred. In addition, polyfunctional methacrylate monomers such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and allyl methacrylate; and polyfunctional vinyl monomers such as vinyl butyrate and vinyl stearate are included. . Among these, triallyl cyanurate (TAC) and triallyl isocyanurate (TAIC) are preferable.

  The amount of the crosslinking aid (C) in the present invention is 0.1 to 5 parts by mass, preferably 0.5 to 5 parts by mass, more preferably 0.5 to 100 parts by mass with respect to 100 parts by mass of the propylene resin. 4 parts by mass. When the blending amount of the crosslinking aid (C) is within the above range, a crosslinked product having a high effect on crosslinking property and excellent in scratch resistance and heat resistance can be produced.

<Inorganic filler (D)>
The propylene-based resin composition used in the present invention may further contain an inorganic filler (D) as an optional component.

  There is no restriction | limiting in particular as an inorganic filler (D) used by this invention, For example, metal compounds, such as a metal hydroxide, metal carbonate (carbonate), a metal oxide; Glass, ceramic, talc, mica etc. Inorganic compounds are widely used. Of these, metal hydroxides, metal carbonates (carbonates), and metal oxides are preferably used. In particular, magnesium hydroxide is preferable. In this invention, an inorganic filler (D) may be used individually by 1 type, and may use 2 or more types together.

  The average particle diameter of the inorganic filler (D) is usually 0.1 to 20 μm, preferably 0.5 to 15 μm. Here, the average particle diameter is a value determined by a laser method.

  The inorganic filler (D) used in the present invention may be a surface treated with a fatty acid such as stearic acid or oleic acid; an organic silane, and the fine particles having the above average particle diameter are aggregated. May be formed.

  The compounding quantity of the inorganic filler (D) in this invention is 30-300 mass parts normally with respect to 100 mass parts of propylene-type resin, Preferably it is 30-280 mass parts, More preferably, it is 40-250 mass parts. When the blending amount of the inorganic filler (D) is in the above range, a crosslinked product having excellent scratch resistance and flame retardancy can be obtained.

<Composition ratio of propylene-based resin composition>
The crosslinked product of the present invention comprises a propylene-based resin (wherein propylene-based polymer (A) and propylene-based polymer (A) and propylene-based polymer (A) and propylene-based polymer (A) The total amount of the propylene polymer (B) is 100% by mass.) The propylene resin composition containing 100 parts by mass and 0.1 to 5 parts by mass of the crosslinking aid (C) is irradiated with ionizing radiation. And obtained by crosslinking. When the content of the propylene polymer (A) and the propylene polymer (B) is in the above range, a crosslinked product excellent in mechanical strength, heat resistance and scratch resistance can be obtained.

≪When using propylene and a C 4-20 α-olefin random copolymer (B-1) as the propylene polymer (B) >>
In the case of using an α-olefin random copolymer (B-1) having 4 to 20 carbon atoms as the propylene polymer (B), the propylene resin is obtained by changing the propylene polymer (A). 15 to 99% by mass, preferably 30 to 99% by mass, more preferably 40 to 99% by mass, further preferably 50 to 99% by mass, particularly preferably 50 to 98% by mass; propylene / carbon atom number of 4 to 20 The α-olefin random copolymer (B-1) is 1 to 85% by mass, preferably 1 to 70% by mass, more preferably 1 to 60% by mass, still more preferably 1 to 50% by mass, particularly preferably 2 to 2%. 50 mass% (here, the total amount of component (A) and component (B-1) is 100 mass%).

  The propylene-based resin composition is a total of 100 parts by mass of the propylene-based polymer (A) and the propylene / α-olefin random copolymer (B-1) having 4 to 20 carbon atoms, that is, the propylene-based resin. It contains 0.1 to 5 parts by mass, preferably 0.5 to 5 parts by mass, and more preferably 0.5 to 4 parts by mass of the crosslinking aid (C) with respect to 100 parts by mass.

<< In the case of using a propylene / α-olefin random copolymer (B-1) having 4 to 20 carbon atoms as the inorganic filler (D) and the propylene polymer (B) >>
When the inorganic filler (D) is used, and when the α-olefin random copolymer (B-1) having 4 to 20 carbon atoms is used, the propylene-based resin is a propylene-based heavy resin. 15 to 99% by mass, preferably 30 to 99% by mass, more preferably 40 to 99% by mass, still more preferably 50 to 99% by mass, particularly preferably 50 to 98% by mass; The α-olefin random copolymer (B-1) of several 4 to 20 is 1 to 85% by mass, preferably 1 to 70% by mass, more preferably 1 to 60% by mass, further preferably 1 to 50% by mass, Particularly preferably, it contains 2 to 50% by mass (here, the total amount of component (A) and component (B-1) is 100% by mass).

  The propylene-based resin composition is a total of 100 parts by mass of the propylene-based polymer (A) and the propylene / α-olefin random copolymer (B-1) having 4 to 20 carbon atoms, that is, the propylene-based resin. 0.1 to 5 parts by weight, preferably 0.5 to 5 parts by weight, more preferably 0.5 to 4 parts by weight, and a propylene polymer (A) with respect to 100 parts by weight of the crosslinking aid (C). ) And a total of 100 parts by mass of propylene / α-olefin random copolymer (B-1) having 4 to 20 carbon atoms, that is, 30 to 30 parts of the inorganic filler (D) with respect to 100 parts by mass of the propylene resin. 300 parts by mass, preferably 30 to 280 parts by mass, more preferably 40 to 250 parts by mass, still more preferably 50 to 250 parts by mass, and particularly preferably 60 to 250 parts by mass.

  Moreover, in the said propylene-type resin composition, in the range which does not impair the objective of this invention, as other components other than the said component (A), (B), (C) and (D) as needed, Other synthetic resins, other rubbers; Includes antioxidants, heat stabilizers, weather stabilizers, slip agents, antiblocking agents, crystal nucleating agents, pigments, hydrochloric acid absorbents, copper damage inhibitors, etc. It may be.

  The blending amount of the other synthetic resin, other rubber, additive and the like is not particularly limited as long as the object of the present invention is not impaired. For example, 100% by mass of the propylene resin composition (however, the crosslinking aid is used). The total of the propylene polymer (A) and the propylene polymer (B), that is, the propylene resin is 60 to 100% by mass with respect to the agent (C) and the inorganic filler (D). The aspect contained so that it may become is preferable, and the aspect contained so that it may become 80-100 mass% is more preferable. The balance is the above-mentioned other synthetic resin, other rubber, additive, etc., excluding the crosslinking aid (C) and the inorganic filler (D).

<Crosslinking>
As a manufacturing method of the crosslinked body obtained by irradiating the propylene-based resin composition with ionizing radiation and crosslinking, a known method can be used without any particular limitation. For example, (i) the propylene-based polymer (A), the propylene-based polymer (B), the crosslinking aid (C) and the other components blended as necessary, or (ii) the propylene-based polymer ( A), the propylene-based polymer (B), the crosslinking aid (C), the inorganic filler (D), and other components to be blended as required are mechanically used using an extruder, a kneader, or the like. A method of irradiating a predetermined amount of ionizing radiation after blending can be mentioned.

  Specifically, the method for producing a crosslinked body of the present invention includes a step of producing a molded product by molding the propylene resin composition into various shapes using a conventionally known melt molding method, and the like. A step of irradiating an object with ionizing radiation and crosslinking. In this way, the above-mentioned crosslinked product of the present invention can be obtained.

  Examples of conventionally known melt molding methods include extrusion molding, rotational molding, calendar molding, injection molding, compression molding, transfer molding, powder molding, blow molding, and vacuum molding.

  As the ionizing radiation, α rays, β rays, γ rays, electron beams, neutron rays, X rays, and the like are used. Of these, cobalt-60 γ rays and electron beams are preferred, and electron beams are particularly preferred. Moreover, although the irradiation amount of ionizing radiation is based also on the kind, when using an electron beam, it is 10-300 kGy normally, Preferably it is 20-250 kGy.

<Physical properties of crosslinked product>
In the case where the crosslinked material of the present invention does not contain the inorganic filler (D), the heat deformation rate is preferably 15% or less, more preferably 10% or less. Moreover, it is preferable that the loss wear amount which is an evaluation standard of scratch resistance is 1.2 mg or less.

  In the case of blending the inorganic filler (D), the crosslinked product of the present invention preferably has a heat deformation rate of 18% or less, and a loss wear amount that is an evaluation standard of scratch resistance is 1.0 mg. The following is preferable.

  The heat deformation rate can be measured at a temperature of 180 ° C. and a load of 1.1 kg according to JIS C3005 using a sheet produced by a press molding machine in accordance with ASTM D2240. it can.

  Further, the loss wear amount, which is an evaluation standard for scratch resistance, can be obtained as follows. Using a scrape wear tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), produced with a press molding machine using a piano wire with a tip shape of 0.45 mmφ attached to the tip of a SUS wear indenter with a weight of 700 g. The surface of the test piece 40 mm long, 1/4 inch wide and 3 mm thick is rubbed and worn. The test conditions are room temperature, 1000 reciprocations, 60 reciprocations / min, and 10 mm stroke. In this way, the mass of the test piece before and after abrasion is measured, and the difference can be obtained as the loss wear amount. The smaller the value of loss wear, the better the scratch resistance.

(Crosslinked molded product)
The crosslinked molded article of the present invention comprises a crosslinked product obtained by irradiating the propylene-based resin composition with ionizing radiation and crosslinking. The cross-linked molded body may form a composite with a molded body made of another material, such as a laminate.

  The cross-linked molded body includes, for example, a coating layer such as an electric wire insulator or electric wire sheath; industrial materials such as sheets, daily necessities, building materials, miscellaneous goods, wallpaper, gaskets and skin materials; automobile parts, vehicle interior materials; It can be suitably used for footwear such as sandals; civil engineering materials. As an example, when used as a coating layer for the wire insulator or wire sheath, the coating layer made of the propylene resin composition is formed around the conductor by a conventionally known method such as extrusion molding. After that, by irradiating with an electron beam and crosslinking, an electric wire insulator or electric wire sheath can be obtained.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.

<Propylene polymer (A)>
As the propylene polymer (A), the following isotactic block polypropylene: b-PP was used.
Propylene / ethylene block copolymer: Melting point (Tm): 160 ° C., MFR (temperature 230 ° C., load 2.16 kg): 0.5 g / 10 min, content of ethylene-derived structural unit: 14.3 mol %, N-decane soluble content; 12% by mass.

<Propylene polymer (B)>
The propylene / 1-butene copolymer (B-1): PBR described below was used as the propylene polymer (B).
Propylene / 1-butene copolymer: Melting point (Tm): 75 ° C., MFR = 7 g / 10 min, 1-butene-derived constituent unit content: 26 mol%, molecular weight distribution (Mw / Mn): 2 .1, Crystallinity (WAXD method); 28%.

<Crosslinking aid (C)>
Triallyl isocyanurate (TAIC) was used as a crosslinking aid (C).

<Inorganic filler (D)>
Magnesium hydroxide (Mg (OH) ₂ , trade name: Kisuma 5B, manufactured by Kyowa Chemical Co., Ltd.) was used as the inorganic filler (D).

<Ethylene polymer (E)>
Linear low density polyethylene (LLDPE) (density: 923 kg / m ³ , MFR (temperature 190 ° C., load 2.16 kg): 2.0) was used.

<Peroxide (F)>
Dicumyl peroxide (manufactured by Kayaku Akzo Co., Ltd.) (hereinafter also referred to as “DCP”) was used as the peroxide (F).

<Measuring method of physical properties of each component>
The physical property values of the respective components were measured as follows.

(1) Content of structural unit derived from comonomer (ethylene, 1-butene)
^It was determined by analysis of ¹³ C-NMR spectrum.

(2) Melt flow rate (MFR)
Based on ASTM D1238, the measurement was performed at a temperature of 230 ° C. and a load of 2.16 kg.

(3) Melting point (Tm)
An exothermic / endothermic curve was determined using a differential scanning calorimeter (DSC), and the temperature at the apex of the melting peak where ΔH during temperature rise was 1 J / g or more was defined as the melting point (Tm).

  In the measurement, the sample was packed in an aluminum pan, heated to 200 ° C. at 100 ° C./min and held at 200 ° C. for 5 minutes, then cooled to −150 ° C. at 10 ° C./min, and then at 200 ° C./min. It calculated | required from the heat_generation | fever / endothermic curve at the time of heating up to degreeC.

(4) Molecular weight distribution (Mw / Mn)
It measured at 140 degreeC using the ortho dichlorobenzene solvent by GPC (gel permeation chromatography) by polystyrene conversion.

(5) Crystallinity degree It calculated | required by the analysis of the wide angle X-ray profile measured using RINT2500 (made by Rigaku Corporation) as a measuring apparatus, and using CuK (alpha) as an X-ray source.

<Evaluation items for crosslinked product>
(1) Strength at break (TS) and elongation at break (EL)
In accordance with ASTM D2240, a press sheet having a thickness of 2 mm is prepared by a press molding machine, and the strength at break (TS) and elongation at break (EL) are measured using this sheet in accordance with JIS K7113-1. It was measured.

(2) Heat deformation rate According to ASTM D2240, a press sheet having a thickness of 2 mm is produced by a press molding machine, and this sheet is used to heat at a temperature of 180 ° C. and a load of 1.1 kg according to JIS C3005. The deformation rate was measured.

(3) Scratch resistance Using a scrape wear tester (manufactured by Yasuda Seiki Seisakusho), with a piano wire with a tip of 0.45 mmφ attached to the tip of a SUS wear indenter with a weight of 700 g. Measure the mass of the test piece before and after abrasion when the surface of a 40 mm long, 1/4 inch wide, 3 mm thick test piece made with a press molding machine was worn. Calculated as a quantity. The test conditions are room temperature, 1000 reciprocations, 60 reciprocations / min, and 10 mm stroke.

[Example 1]
Each raw resin component was kneaded with a lab plast mill (manufactured by Toyo Seiki Co., Ltd.) with the blending amounts shown in Table 1. Subsequently, this was formed into a sheet having a thickness of 2 mm by a press molding machine (heating: 190 ° C., 7 minutes, cooling: 15 ° C., 4 minutes, cooling rate: about 40 ° C./minute). Next, this sheet was irradiated with an electron beam in air under the conditions of an acceleration voltage of 2000 kV and an electron dose of 100 kGy to prepare a crosslinked body.

  Next, the strength at break, elongation at break, heat deformation rate and scratch resistance were evaluated. The evaluation results are shown in Table 1.

[Comparative Example 1]
Except not performing the bridge | crosslinking by electron beam irradiation, the resin composition which consists of the compounding quantity of Table 1 was manufactured like Example 1, and the sheet | seat was shape | molded and the physical property evaluation was performed then. The evaluation results are shown in Table 1.

[Comparative Example 2]
Example 1 except that propylene / 1-butene copolymer is not used as the propylene polymer (B), that is, only the isotactic block polypropylene which is the propylene polymer (A) is used as the resin component. in the same manner to produce a resin composition comprising blending amount described in Table 1, followed by molding the sheet, subjected to electron beam irradiation were things evaluation. The evaluation results are shown in Table 1.

[Comparative Example 4]
A resin composition having the blending amounts shown in Table 1 was kneaded with two rolls set at a temperature of 120 ° C., and then a sheet was formed. Then, it heated and pressurized for 30 minutes with the press molding machine heated at the temperature of 160 degreeC, and the crosslinked body by a peroxide (F) was obtained. The evaluation results are shown in Table 1.

In Table 1, “melting” indicates that the sample was insufficient in heat resistance, so that the initial shape was not maintained at a temperature of 180 ° C. during measurement of the heat distortion rate, and measurement was impossible.

  The crosslinked product of the present invention is a crosslinked product using only the isotactic block polypropylene as the propylene polymer (A) as a resin component, or only the propylene / 1-butene copolymer as the propylene polymer (B). Compared to a crosslinked product using, the strength at break and elongation at break are excellent, and since the heat deformation rate is small, it is clear that the heat resistance is excellent.

[Example 2, Comparative Example 5]
The physical properties were evaluated in the same manner as in Example 1 except that the resin composition was changed to the amount shown in Table 2. The evaluation results are shown in Table 2.

[Comparative Example 6]
Instead of the propylene polymer (A) and the propylene polymer (B), an ethylene polymer (E) was used, and a resin composition having the blending amounts shown in Table 2 was obtained in the same manner as in Example 1. Then, the sheet was molded and the physical properties were evaluated. The evaluation results are shown in Table 2.

[Comparative Example 7]
A resin composition having the blending amounts shown in Table 2 was kneaded with two rolls set at a temperature of 120 ° C., and then a sheet was formed. Then, it heated and pressurized for 30 minutes with the press molding machine heated at the temperature of 160 degreeC, and the crosslinked body by a peroxide (F) was obtained. The evaluation results are shown in Table 2.

[Comparative Example 8, Comparative Example 9]
A resin composition having the blending amounts shown in Table 2 was produced in the same manner as in Example 1 except that the crosslinking aid (C) was not used, and then the physical properties were evaluated by molding a sheet. The evaluation results are shown in Table 2.

  The cross-linked product of the present invention obtained by cross-linking a resin composition containing an inorganic filler (D) (magnesium hydroxide) is excellent in strength at break and elongation at break, and has a low heat deformation rate, thus being heat resistant. It is clear that it is excellent in performance. In particular, the effect is remarkable when compared with Comparative Example 6 using an ethylene polymer (E) instead of the propylene polymer (A) and the propylene polymer (B).

  The cross-linked product of the present invention obtained by irradiating a propylene resin composition with ionizing radiation is an insulating material for electric wires, electric wire sheaths, daily necessities, building materials, sundries, wallpaper, industrial materials such as gaskets / skin materials, automobile parts, It can be suitably used for vehicle interior materials, footwear such as shoe soles and sandals, civil engineering materials, and foamed sheet raw materials.

Claims (8)

15 to 99% by mass of a propylene polymer (A) having a melting point of 120 to 170 ° C. measured with a differential scanning calorimeter (DSC), a melting point of 100 ° C. or less measured with a differential scanning calorimeter (DSC), Alternatively, 100 parts by mass of a propylene-based resin containing 1 to 85% by mass of the propylene-based polymer (B) whose melting point is not observed (the total amount of the component (A) and the component (B) is 100% by mass). ,
A crosslinked product obtained by crosslinking a propylene-based resin composition containing 0.1 to 5 parts by mass of a crosslinking aid (C) by irradiating with ionizing radiation.   The crosslinked body according to claim 1, wherein the propylene-based resin composition further includes 30 to 300 parts by mass of an inorganic filler (D) with respect to 100 parts by mass of the propylene-based resin.   The cross-linked product according to claim 2, wherein the inorganic filler (D) is at least one selected from a metal hydroxide, a metal carbonate, and a metal oxide.   The crosslinked product according to any one of claims 1 to 3, wherein the crosslinking assistant (C) is triallyl cyanurate or triallyl isocyanurate. The propylene polymer (A) contains 50 to 100 mol% of a propylene-derived structural unit and 0 to 50 mol% of a structural unit derived from an α-olefin having 2 to 20 carbon atoms other than propylene (where, The total of the structural unit derived from propylene and the structural unit derived from α-olefin having 2 to 20 carbon atoms other than propylene is 100 mol%).
The propylene polymer (B) contains 40 to 100 mol% of propylene-derived structural units and 0 to 60 mol% of structural units derived from α-olefins having 2 to 20 carbon atoms other than propylene (where, (The total of the structural unit derived from propylene and the structural unit derived from α-olefin having 2 to 20 carbon atoms other than propylene is 100 mol%.)
The crosslinked body in any one of Claims 1-3.   The manufacturing method of the crosslinked body which includes the process of shape | molding the propylene-type resin composition in any one of Claims 1-3, and manufacturing a molded object, and the process of irradiating this molded object with ionizing radiation, and bridge | crosslinking.   The crosslinked molded object which consists of a crosslinked body in any one of Claims 1-3.   The cross-linked molded article according to claim 7, which is an electric wire insulator or electric wire sheath.